Efforts to more economically provide lightweight, long life structures subject to stress and related fatigue, such as airframes for the assembly of aircraft, have resulted in increasing use of thermoplastic and/or related composite materials. The development of various composite materials, and methods of fabricating structures using such materials, has highlighted an as yet unmet need for a process that might be utilized to efficiently, effectively, and reliably join thermoplastic or composite materials together.
In general, design methods associated with prior art welding of various types of plastics have encountered various difficulties. Some methods previously suggested have had or would have difficulty, as a practical matter, in reliably joining components together. For example, the use of welding of thermoset type materials has not been widely utilized in structures that require reliable joint life.
As a consequence of difficulties with thermoset materials, interest has grown in the potential for use of thermoplastic materials in airframe construction, or for other aerostructures. A key issue, however, is how to provide strength, particularly in the “Z” direction, in a joint between two thermoplastic component parts. Thus, there remains a need for a method for fabrication of a composite structure that is capable of reliably joining thermoplastic material parts. Moreover, it would be advantageous to provide a method which facilitates the assembly of parts made from materials desirable for use in aerostructures, such as polyetheretherketone (“PEEK”).
The foregoing figures, being merely exemplary, contain various elements that may be present or omitted from actual apparatus that may be constructed to practice the methods taught herein, and to manufacture the composite structures as set forth herein. An attempt has been made to draw the figures in a way that illustrates at least those elements that are significant for an understanding of the various methods taught herein for the manufacture of composite structures. However, various other elements for a method of manufacture of composite structures using thermoplastic welding using heated inserts may be utilized in order to provide composite structures.